1. Field of the Invention
The present invention pertains more generally to the field of communications systems and, more particularly, to wireless communications, for examples cellular networks.
It can be applied to any communications system in which the structure of the data transmitted does not comprise any intrinsic system for differentiating between the different users if they are making simultaneous transmission (as is the case, for example with CDMA codes which are used to used to identify the different transmitters).
The system according to the invention can be applied more particularly to dedicated unicast or multicast communications (in which one point corresponds to a receiver or to a transmitter having one or more antennas).
2. Description of the Prior Art
Most present-day communications systems generally make use of a single transmission antenna. Consequently, the capacity of the transmission channel or the maximum achievable bit rate for the data transmitted is fairly low.
There are also known ways of using spread-spectrum codes such as the CDMA (Code Division Multiple Access) to exploit the (channel) diversity of a communications system such as the UMTS (Universal Mobile Telecommunications System).
The U.S. Pat. No. 6,115,427 discloses a method and a system to augment the data bit rate in a transmission system and provide a diversity of antennas by using several transmit and receive antennas. This method relies mainly on a step for the space-time encoding of the data at transmission in order to differentiate between the different data streams and to detect them in conjunction.
The drawback of these methods, especially, is that their implementation leads to a modification of the transmission or communications systems, for example the modification of existing transmitters or receivers.